1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a method for forming a pattern in a liquid crystal display device. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for forming a fine pattern and increasing productivity.
2. Discussion of the Related Art
In display devices, particularly in flat panel display devices, pixels are arranged in a matrix form. Among the flat panel devices, liquid crystal display (LCD) devices have active devices, such as thin film transistors (hereinafter, TFTs), which are positioned in respective pixels for driving the pixels in the display devices. Such a method of driving the display device is called an active matrix driving method because the active devices are arranged in the respective pixels aligned in a matrix form.
FIG. 1 is a plane view of a pixel in the related art LCD device using the active matrix method. The active device is a TFT 10. As shown in FIG. 1, a plurality of gate lines 2 arranged horizontally and a plurality of data lines 4 arranged vertically define a pixel. The TFT 10 for independently controlling the driving of the respective pixel is formed near the intersection each of the gate lines and each of the data lines. The TFT 10 includes a gate electrode 2a connected to one of the gate lines 2, a semiconductor 5 formed on the gate electrode 2a, and source and drain electrodes 4a and 4b formed on the semiconductor layer 5. The TFT 10 is activated when a scan signal is applied to the gate electrode 2a by one of the gate lines 2. At the pixel, a pixel electrode 7, which is connected to the drain electrodes 4b, is supplied with an image signal through the source and drain electrodes 4a and 4b, when the semiconductor layer 5 is activated by the gate electrode 2a. The pixel electrode 7 is connected to the drain electrode 4b through a first contact hole 8a. A storage line 6 and a storage electrode 11, which overlaps the storage line 6, are positioned in the pixel defined by the gate line 2 and the data line 4 to form a storage capacitor Cst. The storage electrode 11 is connected to the pixel electrode 7 through a second contact hole 8b. 
FIG. 2 is a cross-sectional view taken along line I—I of FIG. 1 illustrating a TFT 10 and a storage capacitor Cst positioned inside the pixel. As shown in FIG. 2, the TFT 10 includes a substrate 1 formed of a transparent insulating material, such as glass, a gate electrode 2a formed on the substrate 1, a gate insulating layer 13 deposited over the entire substrate 1, a semiconductor layer 5 formed on the gate insulating layer 13, source/drain electrodes 4a and 4b formed on the semiconductor layer 5, a passivation layer 15 formed on the source/drain electrodes 4a and 4b to protect the device, and a pixel electrode 7 connected to the drain electrode 4b through the first contact hole 8a. 
The storage capacitor Cst includes a storage line 6 formed at the same series of patterning processes as the gate electrode 2a of the TFT, and a storage electrode 11 formed at the same series of patterning processes as the source and drain electrodes 4a and 4b. A gate insulating layer 13 is formed between the storage line 6 and storage electrode 11. A second contact hole 8b for exposing a portion of the storage electrode 11 is formed in the passivation layer 15. The storage electrode 11 is electrically connected to the pixel electrode 7 through the second contact hole 8b. The storage capacitor Cst charges through a gate voltage while a gate signal is applied to the gate electrode 2a, and then holds charges until the gate electrode 2 is selected in the next frame to prevent the voltage change of the pixel electrode 7. Herein, sizes of the first and second contact holes 8a and 8b for electrically connecting the drain electrode 4b and the storage electrode 11 to the pixel electrode 7 are a few micrometers (μm), respectively.
The above-described LCD device is fabricated by a photo mask process, and the photo mask process includes a series of processes, such as photoresist application, arrangement and exposure, development, cleaning, etc. More specifically, in the exposure process, processes of disposing the mask on an original position, aligning the mask and the substrate as matching align keys of the mask and the substrate, and radiating a light source are proceeded in order. Herein, it is difficult to form an accurate alignment due to a limitation of the exposing equipment. Therefore, there is a limit in forming a fine pattern requiring a high degree of accuracy, and a plurality of photo processes should be repeated, thereby decreasing the productivity.